Coal bin



FIG. 1 is a top plan view of one embodiment of a coal bin showing my newdesign;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a bottom plan view thereof; and

FIG. 5 is a side elevational view thereof.

The ornamental design for a coal bin, as shown and described.